Service to the Holy Prophet (sa) in his final illness
The service rendered by Hazrat Ali (ra) to the Holy Prophet (sa) during his final illness has been mentioned in a narration in Bukhari as follows:
Ubaidullah bin Abdillah has related that Hazrat Aisha (ra) used to say, “When the Holy Prophet (sa) became ill and his illness intensified, he sought permission from the rest of his wives for me to take care of him in my home; hence, they granted him permission. Following this, he left the house with the support of two men, whilst his feet were leaving a trail on the ground [as a result of the weakness in his body]. He was being supported by Hazrat Abbas (ra) and another individual.”
In other words, he was already in the home of Hazrat Aisha (ra) at the time and left her house with the support of two men in order to go to the mosque. Ubaidullah narrates that he mentioned what Hazrat Aisha (ra) had narrated to him to Hazrat Ibn Abbas (ra), upon which he enquired whether he knew the individuals whom Hazrat Aisha (ra) mentioned. Ubaidullah replied in the negative and Hazrat Ibn Abbas (ra) stated that she mentioned Hazrat Abbas (ra) and the other individual, who she did not name was Hazrat Ali (ra) bin Abi Talib.
(Sahih al-Bukhari, Kitab al-Azan, Bab Hadd al-Marid yashhadu al-Jama‘ah, Hadith 665)